Is there a way to make slight imperfections on a model? (golden ring)
You could sculpt a high-poly version and bake the normals, but I guess the easiest way to do it is to fake with a procedural texture. Here is a chain of nodes that works in my opinion: Texture Coordinate (Object output) > Mapping > Vector input of a Noise Texture > Height input of a Bump > Normal input of a Glossy > Material Output. Note that you can play with the Noise Texture node parameters to make the defaults bigger or smaller:



Also, if you want some more or less glossy surface parts, you can plug a Noise Texture node into the factor of a Mix Shader so that it separates 2 different Glossy shaders.